Department of Virology and Parasitology, Fujita Health University School of Medicine, Kutsukakecho, Toyoake, Aichi, Japan.
Department of Virology and Parasitology, Fujita Health University School of Medicine, Kutsukakecho, Toyoake, Aichi, Japan
J Virol. 2014 Jun;88(12):6586-98. doi: 10.1128/JVI.00208-14. Epub 2014 Mar 26.
Phosphatidylinositol 4-kinase IIIβ (PI4KB) is a host factor required for the replication of certain picornavirus genomes. We previously showed that nonstructural proteins 2B, 2BC, 2C, 3A, and 3AB of Aichi virus (AiV), a picornavirus, interact with the Golgi protein, acyl-coenzyme A binding domain containing 3 (ACBD3), which interacts with PI4KB. These five viral proteins, ACBD3, PI4KB, and the PI4KB product phosphatidylinositol 4-phosphate (PI4P) colocalize to the AiV RNA replication sites (J. Sasaki et al., EMBO J. 31:754-766, 2012). We here examined the roles of these viral and cellular molecules in the formation of AiV replication complexes. Immunofluorescence microscopy revealed that treatment of AiV polyprotein-expressing cells with a small interfering RNA targeting ACBD3 abolished colocalization of the viral 2B, 2C, and 3A proteins with PI4KB. A PI4KB-specific inhibitor also prevented their colocalization. Virus RNA replication increased the level of cellular PI4P without affecting that of PI4KB, and individual expression of 2B, 2BC, 2C, 3A, or 3AB stimulated PI4P generation. These results suggest that the viral protein/ACBD3/PI4KB complex plays an important role in forming the functional replication complex by enhancing PI4P synthesis. Of the viral proteins, 3A and 3AB were shown to stimulate the in vitro kinase activity of PI4KB through forming a 3A or 3AB/ACBD3/PI4KB complex, whereas the ACBD3-mediated PI4KB activation by 2B and 2C remains to be demonstrated.
The phosphatidylinositol 4-kinase PI4KB is a host factor required for the replication of certain picornavirus genomes. Aichi virus, a picornavirus belonging to the genus Kobuvirus, forms a complex comprising one of the viral nonstructural proteins 2B, 2BC, 2C, 3A, and 3AB, the Golgi protein ACBD3, and PI4KB to synthesize PI4P at the sites for viral RNA replication. However, the roles of this protein complex in forming the replication complex are unknown. This study showed that virus RNA replication and individual viral proteins enhance the level of cellular PI4P, and suggested that the viral protein/ACBD3/PI4KB complex plays an important role in forming a functional replication complex. Thus, the present study provides a new example of modulation of cellular lipid metabolism by viruses to support the replication of their genomes.
磷酸肌醇 4-激酶 IIIβ（PI4KB）是一种宿主因子，是某些小核糖核酸病毒基因组复制所必需的。我们之前曾表明，小核糖核酸病毒 Aichi 病毒（AiV）的非结构蛋白 2B、2BC、2C、3A 和 3AB 与高尔基蛋白酰基辅酶 A 结合域包含 3（ACBD3）相互作用，后者与 PI4KB 相互作用。这五种病毒蛋白、ACBD3、PI4KB 和 PI4KB 产物磷脂酰肌醇 4-磷酸（PI4P）在 AiV RNA 复制部位共定位（J. Sasaki 等人，EMBO J. 31:754-766, 2012）。在这里，我们研究了这些病毒和细胞分子在形成 AiV 复制复合物中的作用。免疫荧光显微镜显示，用靶向 ACBD3 的小干扰 RNA 处理表达 AiV 多蛋白的细胞会使病毒 2B、2C 和 3A 蛋白与 PI4KB 的共定位消失。PI4KB 特异性抑制剂也阻止了它们的共定位。病毒 RNA 复制增加了细胞 PI4P 的水平，而不影响 PI4KB 的水平，单独表达 2B、2BC、2C、3A 或 3AB 刺激 PI4P 的产生。这些结果表明，病毒蛋白/ACBD3/PI4KB 复合物通过增强 PI4P 合成在形成功能性复制复合物中发挥重要作用。在病毒蛋白中，3A 和 3AB 被证明通过形成 3A 或 3AB/ACBD3/PI4KB 复合物来刺激 PI4KB 的体外激酶活性，而 2B 和 2C 介导的 ACBD3 对 PI4KB 的激活仍有待证明。
磷酸肌醇 4-激酶 PI4KB 是某些小核糖核酸病毒基因组复制所必需的宿主因子。Aichi 病毒是一种小核糖核酸病毒，属于 Kobuvirus 属，形成一种包含一种病毒非结构蛋白 2B、2BC、2C、3A 和 3AB、高尔基蛋白 ACBD3 和 PI4KB 的复合物，以在病毒 RNA 复制部位合成 PI4P。然而，该蛋白复合物在形成复制复合物中的作用尚不清楚。本研究表明，病毒 RNA 复制和单个病毒蛋白可提高细胞内 PI4P 的水平，并表明病毒蛋白/ACBD3/PI4KB 复合物在形成功能性复制复合物中发挥重要作用。因此，本研究为病毒调节细胞脂质代谢以支持其基因组复制提供了新的例证。
